/*TER/ The
National Transportation Safety Board (NTSB) noted that in 1999, the
ORD (CCA9018/KAL036), JFK (ICE614/AFR6498), and LAX (AMX432/UAL204)
runway incursion incidents involved flight crews whose primary
language was not English. Based on these incidents, the NTSB
recommended that controllers speak at reasonable rates when
communicating with all flight crews, especially to those whose primary
language is not English. International pilots may have difficulty
comprehending air traffic control (ATC) instructions that are not
communicated at reasonable speech rates. To minimize chances for
misunderstanding instructions, we encourage controllers to speak at
reasonable rates when communicating with all flight crews. (ATP-120)

The following is a description of a serious
situation that could have become a tragic accident. As you read
through the summary, take a moment to consider whether you could have
been caught in the same trap. The most valuable lesson is one that can
be learned without having to go through bitter experience to do so.

THE FRAMEWORK FOR AN ACCIDENT

THE STAGE

Runways 22
and 29L cross each other and were both active. Taxiway Charlie runs
parallel with runway 29L and is located on its south side.

THE PLAYERS

N9231C, a PA28
N75231, a PA28
Local Control

THE SITUATION

Local control instructed N9231C to taxi into
position and hold on runway 22 because another aircraft was departing
on runway 29L. Meanwhile, N75231 had completed his preflight run up
check and was ready to depart on runway 22 from the intersection of
runway 22 and taxiway Charlie. The local controller responded,
"N231 runway 22 intersection Charlie cleared for takeoff."

THE RESULT

The pilot
of N9231C and N75231 both responded to the clearance simultaneously
and N9231C got airborne first. When the controller saw it, the
aircraft's nose wheel was leaving the ground. The controller was able
to stop N9231C's takeoffin
order to avoid a collision, and the pilot was able to stop his
aircraft 900 feet behind N75231.

WHAT HAPPENED? WHO WAS AT FAULT?

Obviously, N9231C took the clearance intended for
N75231. However, if we look at the circumstances of this incident
carefully, we can see how the links in the chain of events were built,
and how, although inadvertently, ATC aided the process.

THE ANALYSIS

Notice the similarity and coincidence of the call
signs themselves: N231Charlie and N231. Both call signs contain the
numerals, 231. The word, "Charlie," is connected to both
aircraft, although in different ways. "Charlie" is part of
the aircraft's call sign for one aircraft, and for the other aircraft,
"Charlie" is its location on the airfield. Both aircraft are
the same type.

Now let's look at the situation from the point of
view of the pilot of N9231C. He has been instructed to taxi onto the
runway and wait there due to a departure off runway 29L that will
cross runway 22 downfield. By putting the aircraft into position on
the runway, two expectations have been built – – first, that
takeoff clearance is being withheld only momentarily, and second, that
as soon as the runway 29L departure is through the intersection,
takeoff clearance can be expected to follow. In other words, the next
thing the pilot expects the controller to say is, "cleared for
takeoff," not an unreasonable expectation if you think about it.

However, from the controller's point of view, the
situation is quite different. One aircraft is not going anywhere
because it is holding in position on the runway. The other aircraft is
ready to go at the intersection. With the runway 29L departure out of
the way, there was an opportunity to quickly get the intersection
departure airborne, and the controller decided to take advantage of
that opportunity.

THE MISTAKE

The controller inadvertently set a trap for the
pilot holding on the runway. Here is an analogy to explain what we
mean.

Sprinters are lined up at the starting line for a
foot race. The starter calls out, "Ready…Set…Joe, get that
dog off the track!" Do you think any of the runners would still
be poised waiting for the word, "Go?" I doubt it. Most
likely all would have started off the blocks as fast as they could
run. This is what happens when a person is primed for a certain
expectation.

In the case of the two pilots, the pilot holding
in position had been primed to expect takeoff clearance after the
runway 29L departure was out of the way. In addition, the curious
combination of call signs, aircraft types, and the word,
"Charlie," made it much easier for the pilot to believe that
the clearance was intended for him. The other pilot, N75231, may or
may not have been aware of N9231C holding in position, but even if he
was, the clearance was clearly directed to his aircraft and his
expectation obviously was that the holding aircraft would continue to
hold.

HOW DO WE PREVENT
SUCH NEAR DISASTERS?

Be alert for similar sounding words, call signs
or situations where an unintended link can be made.

Do not leave aircraft in position on runways for
periods of greater than 30 to 60 seconds. It is too easy to forget
they are there, or for them to forget they are supposed to be holding
and to begin a premature takeoff.

Whenever you have an aircraft in position on a
runway and you decide to cross traffic down field, or to depart
traffic from another runway or from the intersection of the runway the
aircraft is holding on, ALWAYS tell the holding pilot to continue
holding and why BEFORE you issue the other clearance. Example:
"N1234, HOLD IN POSITION, traffic will be crossing
downfield." And get a correct acknowledgment! This is extremely
important when the pilot has been primed to expect a different
sequence of events.

Be alert for heterodyning. When more than one
aircraft transmits a message at the same time, you will often hear
heterodyning, a squealing or garbled noise through your radio
receiver. This should ALWAYS be a clue to you that two or more
aircraft are responding to what you said. In the case of our
discussion, controllers should IMMEDIATELY suspect that the holding
aircraft is responding, even if that turns out to be untrue. Because
the pilot is in a position to cause great havoc if he does something
other than continue holding in place, it is the first place to look
for trouble and head it off. Reiterate that the holding aircraft
should continue doing so.

Never assume that the holding aircraft's pilot
can see an aircraft that is crossing or departing from an intersection
downfield. Although the runway may appear to be as flat as a pancake
from your perspective, keep in mind that many runways have gradients
that make it impossible for pilots in certain positions to see another
aircraft on or near the same runway. Tell the pilot.Do not assume they can see "what is plainly in front of
their faces" for truly, it may not be as plain a sight as you
believe!

Part of being successful in this business is
cultivating the ability to analyze situations quickly and accurately
to stay ahead of the game. Try to be alert to situations where
mistakes can be made. Think to yourself, "What is the worst thing
this pilot could do right now to mess me up or cause an
incident?" If you can do that and prepare so that it can be
avoided, then your career as an air traffic control specialist may be
blissfully uneventful.

Pilots are required to inform ATC when
navigation, approach, or communication equipment malfunctions occur
during flight (CFR 91.187). This announcement makes sense because the
aircraft's ability (or inability) to navigate, directly affects the
controller. If the aircraft's sole VOR receiver quits working, then
the aircraft will not be able to navigate on Victor or Jet airways.
Unless the aircraft has a backup navigation system, the flight will be
dependent upon the controller for navigation assistance in the form of
radar vectors. And once the aircraft is ready for an approach to its
destination, it would be silly to issue a VOR approach, wouldn't it?

Although not required, sometimes pilots will
share information with you regarding other instrument or mechanical
failures. What does that mean to you? The pilot's mention of the loss
could be a signal to you that the aircraft may soon enter into an
emergency status, or require a little different handling, or may
require no change to your operation at all. Often, the loss or
malfunction of an aircraft component is more or less transparent to
you, the controller, whereas it is a slightly bigger deal for the
pilot.

ELECTRICAL POWER
LOSS

An announcement that the aircraft's electrical
system is compromised by the failure of the alternator or generator
means that the loss of the aircraft's radios, transponder, and some
navigation equipment will probably follow (if it has not already
occurred). Depending on the aircraft, emergency battery power or air
powered turbines may take up the slack for a short period of time, but
if it happens to a small general aviation type aircraft, both you and
the pilot soon will be in the dark. Consider electrical problems a
potential emergency. Prepare to block airspace for a "NORDO"
aircraft and consider what actions the pilot may take. If the aircraft
is in instrument meteorological conditions (IMC), it will continue to
fly its last assigned route, if it is able, but if it encounters VFR
conditions, it may change course and proceed to the nearest airport.
Pay attention because if the aircraft has no electrical power, its
transponder will not be working. This means primary target only for
radar controllers, and losing track of an IFR primary target can cause
a lot of trouble.

WHEN THE PRESSURE
IS OFF

Hydraulic power systems are associated with jet
and turbojet aircraft. Small, general aviation aircraft do not rely on
hydraulic systems to operate their flaps and flight control surfaces.
The loss of hydraulic pressure affects an aircraft's ability to deploy
flaps. This translates into higher approach speeds and longer runway
rollouts. Give the aircraft more room for descents and make certain
you set the aircraft up for a stable approach for landing. High, short
approaches are very much counter productive in these cases! Be aware
that the aircraft may not be able to taxi off the runway due to loss
of nose wheel steering on the ground. In that case, it will need to be
towed to its destination.

LOOK MA, NO WHEELS!

Gear up landings are generally not life
threatening. They are damaging in varying degrees to the aircraft, but
its occupants usually enjoy just a noisy slide down the runway.
However, that being said, always treat a gear up landing as an
emergency because there is always the chance that a wing tip may get
too low and drag during the approach. If this happens, there is a
chance that the aircraft may cartwheel out of control or slide off the
side of the runway and hit whatever is there to hit. If the pilot had
misjudged and comes in too high and fast, there is also the
possibility that the aircraft will go off the end of the runway. You
can help by providing a stable approach to the runway. Again, short,
high, fast approaches are not helpful to the pilot.

HOOVER? BISSEL?
ELECTROLUX? KIRBY?

If a pilot informs you that the aircraft's vacuum
system has failed, what does this really mean? What can you expect? Is
this just "nice-to-know" information? We have an accident on
record where a pilot informed the controller that the aircraft's
vacuum system had failed. The controller duly passed on this
information to the next controller, stating that the aircraft's vacuum
cleaner had quit or something like that. Whether this was an ill-timed
attempt at humor or an honest misinterpretation is hard to say, but it
was clear that neither controller understood the seriousness of the
pilot's predicament. You may not be able to do much about the
difficulties the pilot is having, but there are some things to keep in
mind that will help you avoid aggravating the situation. And yes, the
loss of the vacuum system is serious for the pilot.

The attitude indicator is THE primary instrument,
and its loss is serious. The ability to control the aircraft in IMC
conditions without the attitude indicator is problematic, especially
if turbulence is added to the equation. When a pilot reports a loss of
vacuum, this is the instrument that is usually affected.

A pilot can control the aircraft by reference to
only three instruments during IMC conditions. Those three instruments
are the turn and slip indicators and the airspeed indicator.
Controlling the aircraft with only the three instruments (referred to
as needle/ball/airspeed) is difficult, takes a lot of concentration,
and is very fatiguing. It is a true emergency situation.

Normally, the pilot will rely upon the following
instruments to keep the aircraft under control:

Attitude Indicator/Artificial Horizon: This is a
gyroscopic instrument powered by the aircraft's electrical system or
by a vacuum pump. It enables the pilot to keep the aircraft right side
up. The instrument is almost always powered by a vacuum pump in the
general aviation fleet.

Heading Indicator/Directional Gyro (DG): This is
a gyroscopic instrument powered by the aircraft's electrical system or
vacuum pump. It provides the pilot with an easy to read, steady
display of the aircraft's heading. However, the heading indicator
creeps and must be reset with the magnetic compass about every 15
minutes. More expensive gyros are connected with a magnetic compass in
such a way that the tendency to creep is automatically corrected. This
instrument does not have the oddities that plague the magnetic
compass.

Turn/Bank and Slip Indicator (two instruments in
one): The turn indicator (needle) is a gyroscopic instrument powered
by the aircraft's electrical system or vacuum pump. The needle uses
precession to indicate the direction and approximate rate of turn of
the aircraft. This instrument helps the pilot execute standard rate or
half-standard rate turns. The slip indicator (ball) reacts to
centrifugal/centripetal forces exerted on the aircraft. This
instrument helps the pilot coordinate the input of the aircraft's
rudder and ailerons during turning movements. Both instruments help
the pilot execute coordinated turns. The instrument is almost always
powered by the aircraft's electrical system in the general aviation
fleet.

Altimeter: The altimeter is affected by
atmospheric air pressure. This instrument tells the pilot how high the
aircraft is above sea level.

Airspeed Indicator: The airspeed indicator is
affected by ram air pressure. It is an air pressure gauge calibrated
to read in miles per hour or knots instead of pounds per square foot.

Vertical Speed/Rate of Climb Indicator: This
instrument is affected by air pressure. It indicates the rate of climb
or descent the aircraft is making. Pilots may use the instrument to
maintain a particular rate.

Magnetic compass: The magnetic compass is
affected by acceleration/deceleration, northerly turning error,
magnetic variation and magnetic deviation. Although more difficult to
use, this instrument can provide reliable information on what
direction the aircraft's nose is pointing.

Other than the altimeter, airspeed indicator, and
turn/bank indicator, small, general aviation aircraft gyro instruments
are typically powered by an engine-driven vacuum pump or combination
of pump and electrical system. If the pump fails, those instruments
dependent upon the pump for power will cease to operate. Conversely,
if the aircraft's electrical system fails, then electrically driven
instruments will cease operation. Most single-engine general aviation
aircraft do not have backup systems, that is, the instrument is
powered by either the electrical system or the vacuum system, but not
both.

So, how can you help? If the pilot advises that a
loss of the vacuum or electrical system has occurred, ask the pilot
whether or not assistance is needed. If the answer is "Yes,"
here are some points to keep in mind.

First, do not jump right into issuing the pilot
turns! Let the pilot fly straight ahead. If there is traffic in the
way, move it. If the aircraft is approaching your airspace boundary,
coordinate with the neighboring controller for its use. Do not issue
turns until the pilot indicates that he/she is ready and able to turn
the aircraft. Of course, if the aircraft is approaching terrain or
obstructions, you have no choice but to warn the pilot and suggest a
turn to avoid a collision.

Try to get the aircraft to VFR conditions. If a
climb or descent is necessary, establish the aircraft on a heading
before beginning the change in altitude. Try to avoid issuing altitude
changes concurrent with changes in heading while the aircraft is in
IMC. As stated before, the aircraft can be managed with the three
basic instruments, needle, ball, and airspeed, but it is difficult.
Pilots are required to master "partial panel" control of the
aircraft using only the three instruments and the aircraft's altimeter
and must demonstrate this ability to the flight examiner in order to
pass the instrument flight test to acquire the instrument flight
rating. The skill necessary to achieve success is obtained only after
much diligent practice, but, once the rating is attained, few pilots
ever practice partial panel control of the aircraft again, so the
skill is pretty much lost.

Keep your instructions short and brief. That is,
do not issue a string of commands or questions. Remember, the pilot
has to exert a lot of concentration to keep the aircraft right side
up. Also, an autopilot is useless in this case because it uses the
gyro instruments for guidance just as the pilot would if they were
working!

So if a pilot tells you that the aircraft's
vacuum system is kaput, now you will have a little better idea of what
is going on, and what problems the pilot may be facing… and that it
is not a cleaning problem! (AAT-200)